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calcium and iron

Calcium significantly reduces iron absorption

What's happening

Calcium can reduce iron absorption by up to 50%. This is one of the most significant mineral interactions.

Recommendation

Take iron supplements away from calcium-rich foods or supplements.

Timing

Separate by at least 2-4 hours

Sources

  • — Journal of Nutrition
  • — NIH

Frequently Asked Questions

Can I take calcium and iron together?

Calcium significantly reduces iron absorption. Take iron supplements away from calcium-rich foods or supplements.

How should I time calcium and iron?

Separate by at least 2-4 hours

Is this interaction dangerous?

This interaction is rated “Warning” by Formulate. Calcium can reduce iron absorption by up to 50%. This is one of the most significant mineral interactions.

Want to check your whole stack?

The free checker lets you add any combination of supplements and medications at once. Formulate's desktop app goes further — every stack change surfaces interaction alerts automatically.

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Medical disclaimer. This page is for educational purposes only and does not replace advice from a qualified healthcare provider.